1. Field of the Invention
This invention relates to an RF excited gas laser and more particularly to an RF excited gas laser having an asymmetric dipolar electrode configuration which includes a positive electrode and a negative electrode with cooling tubes and which utilizes a matching network which consists of only an inductor and a variable capacitor.
2. Description of the Prior Art
U.S. Pat. No. 4,891,819, entitled RF Excited Laser with Internally Folded Resonator, issued to Leroy V. Sutter, Jr. and Harold A. Cameron on Jan. 2, 1990, teaches a transversely RF excited gas laser with an internally folded resonator which includes an elongated chamber of cross-sectional dimensions suitable for confining a laser gas discharge, a plurality of reflectors and a laser gas. The reflectors form a stable folded laser resonator cavity of a compact geometry in order to efficiently extract laser power from the laser resonator cavity. There are at least two of the reflectors and at least one of the plurality of reflectors is concave. The laser gas is disposed in the folded resonator cavity which reflect and guide light energy from the laser gas discharge within the elongated chamber. The transversely RF excited gas laser with an internally folded resonator also includes a pair of electrodes and a pair of cooling electrodes. The electrodes are transversely disposed on the elongated chamber and excite the laser gas. The cooling electrodes are transversely disposed on the elongated chamber and electrically coupled to ground. The impedance-matching circuit applies RF power to the electrodes. The impedance-matching circuit includes three inductors with a center-tapped coil being adjusted so that the voltage potential at the center of the laser discharge between the pair of cooling electrodes is a virtual ground thereby preventing RF current from passing through the grounded cooling electrodes in order to efficiently extract laser power from the laser resonator cavity.
U.S. Pat. No. 4,464,760, entitled Elongated Chamber for Use in Combination with a Transversely Excited Gas Laser, issued to Leroy V. Sutter, Jr. on Aug. 7, 1984, teaches an laser bore and electrode structure which includes a ceramic bore, a pair of active electrodes and a pair of cooling electrodes. The active electrodes are electrically coupled to an RF generator through a matching network. The cooling electrodes are grounded.
U.S. Pat. No. 4,500,996, entitled High Power Fundamental Mode Laser, issued to Michael W. Sasnett, James L. Hobart and Larry A. Gibson on Feb. 19, 1985, teaches a high power, fundamental mode gaseous laser which has a discharge-confining bore tube which is provided with spaced-apart annular, inwardly-extending, radial projections which have inside diameters which match the fundamental mode diameter along the tube.